Effects of α‐methyl‐<i>p</i>‐tyrosine, <i>p</i>‐chlorophenylalanine, <scp>l</scp>‐β‐(3,4‐dihydroxyphenyl)alanine, 5‐hydroxytryptophan and diethyldithiocarbamate on the analgesic activity of morphine and methylamphetamine in the mouse

Abstract

1. The analgesic activity of sympathomimetic drugs does not appear to involve a peripheral component.2. Drugs causing changes in morphine analgesia have similar effects on the analgesia produced by methylamphetamine.3. The analgesia produced by morphine and methylamphetamine is increased by drugs which increase the ratio of brain 5-hydroxytryptamine (5-HT) to dopamine.4. The analgesia is decreased by drugs causing a fall in brain 5-HT or a rise in dopamine relative to 5-HT.